1. The Field of the Invention
The present invention is related to a control system for providing pitch, yaw and roll control in a guided projectile. More particularly, the present invention is related to a finless missile control system which utilizes two pairs of opposing flaps to provide control.
2. Technical Background
Increased performance capabilities of tactical aircraft, sea-skimming missiles and other tactical weapons require the development of enhanced missile guidance and control systems to provide a defense to such armaments. Current technology in missile guidance and control systems includes the use of pulse motors and thrust vector control systems.
Pulse motors provide an efficient means of managing the energy of the missile while significantly enhancing missile performance and flexibility. Missiles utilizing pulse motors may be made to be highly maneuverable, particularly under high-g requirements, by incorporating a thrust vector control system in the missile. The terminal homing of a missile is one example of an application requiring a highly maneuverable missile.
Thrust vector control systems have been developed using a variety of means, including movable nozzles, jet tabs, jet vanes and injection of fluid into the nozzle. Of these systems, optimal performance is generally obtained through the use of a movable nozzle. Until recently, however, movable nozzles were not incorporated into small, tactical missiles because they could not be made sufficiently small and light. Recent developments in this area, including the development of advanced elastomeric materials and improved flexible bearing and trapped-ball designs, have yielded viable tactical missiles having vectorable nozzles.
Notwithstanding the availability of vectorable nozzles and pulse motors for use in tactical missiles, such missiles do continue to suffer from some performance limitations. One of the principal disadvantages accompanying the use of thrust vector control systems is that they are ineffective during coast periods. To address this problem, thrust vector control systems have been integrated with aerofins to achieve conventional four-axis aerofin control during coast periods.
The use of fins, however, can significantly reduce the number of missiles which can be packaged into a given cross section, such as the payload bay of an airplane or ship. Consequently, designs have been proposed which utilize flaps or panels which lie flush with the skin of the missile when not in use but which can be actuated to extend into the airstream to control the missile. Such flap systems are generally designed to provide pitch, yaw and roll control.
A significant disadvantage to the use of prior art flap designs is the difficulty in incorporating a design which effectively achieves roll control in addition to yaw and pitch control. In order to induce the aerodynamic forces necessary to provide roll control, the flaps must be capable of actuation at an angle, with one side of the flap extending into the airstream a greater distance than the other. Some designs address this problem by utilizing a triangular shaped flap mounted to the case with a pin joint. An actuator mounted on each side of the flap then provides the capability of actuating one side to a greater degree than the other side, thereby providing roll control. As will be appreciated by one of skill in the art, however, such designs require the use of complex and bulky actuation devices. In many cases, these actuation devices cannot be successfully implemented into a tactical missile while retaining the size and weight of the missile within a desirable range.
From the foregoing, it will be appreciated that it would be an advancement in the art to provide an effective control system which will provide pitch, roll and yaw control in a guided projectile. It would be a further advancement if such a control system would provide control even during coast periods.
It would be an additional advancement in the art if such a control system could be provided which did not utilize fins and which also avoided the use of complicated actuator systems generally necessitated by control systems utilizing flaps.
Such a control system is disclosed and claimed herein.